Suppose there is a patent with claim A that is filed five years ago. It might not be perceived as "obvious" five years ago but it is very common nowadays.
Suppose John wants to file a patent application for his idea that is built on top of claim A.
- Would his patent even get granted?
- Even if it gets granted, if he practised his invention, would he be infringing claim A?
Assuming this is in the US.
To give an example, lets say back in the days when there is only black and white TV, John invented a color TV and it was so innovative at that time the claim "show color on TV" John wrote got granted. A few years later showing color on TV becomes so obvious that it becomes textbook material. Bill comes in with an invention that "shows color on digital TV", Sam comes in with an invention that "shows higher resolution color on TV".
- Would Bill's and Sam's patents get granted?
- If Bill and Sam practised their inventions, could John sue them for patent infringement?